宇航用高可靠复合开关设计

Design of High Reliability Compound Switch for Aerospace Application

传统星载设备采用继电器对供电母线进行开关控制,继电器体积大,并且在大电流情况下,容易产生触点粘连故障,可靠性低。针对该问题提出一种高可靠复合开关电路,采用小型继电器对供电母线上的功率MOS管的栅源电压进行控制,实现了对供电母线的加断电控制;分析了该电路的工作过程,利用功率MOS管线性工作区的特性,可有效降低开机浪涌电流;在此基础上给出了各元器件的降额设计方法。对一款星载DCDC变换器前级增加该开关电路进行试验,结果表明,该开关电路能够可靠控制供电母线的加断电,通过改变缓启电容的大小,能够减小开关浪涌电流90%以上,体积小,可靠性高。

In traditional aerospace equipment,relay is often used to control the power supply bus,but the relay is usually large in volume and the contact adhesion failure is easy to occur in the case of large current,so its reliability is low. Aiming at this problem,a high reliability compound switch circuit was proposed. The power supply bus was controlled to switch by controlling the power MOSFET's gate-to-source voltage with a small relay. Then the working process of the circuit was analyzed. The inrush current could be reduced effectively by using the power MOS tube in the linear region. Also the derating design method of the components was given. A switching circuit was added before a DCDC converter. The experiment results indicated that this switch circuit could control the power supply bus to switch reliably,and the inrush current could be reduced by more than 90%through changing the soft capacitor. The circuit has the advantage of small volume and high reliability.